DESCRIPTION (adapted from the application) This application has 2 components. The first focuses on neuroendocrine cells of the prostate, and a transgenic mouse model (CR2-TAg) of metastatic prostate cancer (CaP) arising from this cell lineage. The functions of neuroendocrine cells in the developing and adult prostate remain incompletely defined. Moreover, the appearance of histologic and biochemical features of neuroendocrine differentiation in human CaP is associated with more aggressive disease and androgen independence. CR2-TAg transgenic mice develop prostatic intraepithelial neoplasia (PIN) by 8 weeks of age. This in situ phase is followed by an invasive phase with eventual metastatic spread to lymph nodes, liver, lung, brain and bone. The distinctiveness of the in situ and invasive phases makes this model useful for characterizing the neuroendocrine cell lineage and for identifying the molecular determinants of invasion of a neuroendocrine cancer. We will use these mice to pursue 3 specific aims: (1). Obtain a molecular signature of neuroendocrine cells following initiation of tumorigenesis, at various stages during progression of this cancer, and in the normal prostate using a combination of Affymetrix GeneChips, in situ hybridization, and a new, generally applicable approach for laser capture microdissection (LCM) that allows recovery of intact mRNA from marked cell populations. (2). Produce neuroendocrine cell lines from CR2-TAg mice. (3). Generate Cre-expressing mice for gene knockouts in prostatic neuroendocrine cells. The second component focuses on the urothelium. The undamaged adult mouse urothelium undergoes very slow turnover, making it difficult to identify the molecular regulators of its renewal. The rapid loss and renewal of the (mouse) urothelium following FimH+-dependent attachment of uropathogenic E. coli (UPEC) provides an opportunity to identify the molecular details of urothelial differentiation/survival, and to obtain new understanding about the molecular pathogenesis of urinary tract infection. Aim 4 will be to use GeneChips to compare gene expression in the bladders of adult female C57Bl/6 mice at various times after exposure to isogenic FimH+ and FimH- strains of UPEC. The cellular origins of observed changes in expression, prior to exfoliation, and during urothelial repair, will be deciphered. The cellular patterns of expression of selected genes will also be characterized in the normal developing and adult urothelium. We have generated transgenic mice that express Cre recombinase in all layers of the urothelium, from the calyces to the bladder, from at least E16.5 through adulthood. In aim 5, we will continue our efforts to develop an inducible system for performing gene knockouts in all layers of the urothelium. These mice will allow future tests of the contributions of various genes to urothelial function in health and disease.